He who wisheth for those things that should not be desired, and forsaketh those that may legitimately be desired, and who beareth malice to those that are powerful, is regarded to be a foolish soul. He who regardeth his foe as his friend, who hateth and beareth malice to his friend, and who committeth wicked deeds, is said to be a person of foolish soul. O bull of the Bharata race, he who divulgeth his projects, doubteth in all things, and spendeth a long time in doing what requireth a short time, is a fool.

In plain words: A fool wants what he shouldn't, gives up what he rightly could have, and holds grudges against the powerful. He trusts his enemy and hates his friend, and does wicked things. He also tells everyone his plans, doubts everything, and takes forever on quick tasks.